Shortwave-Antenna

Description

For various reasons, only a wire antenna that was as inconspicuous as possible could used as a SW antenna (for transmitting). Furthermore, only a bit more than 23m wire length is available. A 32 m2 sheet metal roof can be integrated as an electrical counterweight.

A very cheap clothesline was used as antenna wire (no joke!). This consists of a steel cable (alloy - can even be soldered.) with a plastic sheath. The anchoring consists of a plastic rope and insulating "eggs" made of porcelain and a plastic "dog bone". One fixing point (fixed) is the roof ridge of the house, which has been raised by 1m, the other one is a spruce tree. Here, the guy rope is guided by a pulley and mounted by means of weight (some iron parts) in a movable way.

The length of the antenna is approximately 23m. The height is 10m at the lowest point. The antenna is fed in at an end point. These point is very high impedance, so that a 1:9 unun is looped in for transformation before the 50 Ohm coaxial cable. This is followed by a mantle current barrier. A small plastic housing ensures weatherproofness. This box is hung from the "dog bone". The cold end of the unun is connected to the sheet metal roof and not earthed! The sheet metal roof is a counterweight to the antenna wire (as a consequence a dipol).

The coax line between the plastic housing and a junction box on the side wall of the building is designed with a movable RG58. From the box up to the shack (about 15m) as high quality RG213. A surge arrester follows before the house entry. The whole thing is designed for QRP, but as has been shown, it can withstand 100W SSB.

The transceiver contains an ATU for adaptation (compensation and a little transformation).

Photos


SWA01.jpg
Longwire
SWA02.jpg
Clothesline
SWA03.jpg
Insulators
SWA04.jpg
Insulator
SWA05.jpg
One Point
SWA06.jpg
Other Point
SWA07.jpg
Unun
SWA08.jpg
xxx
SWA09.jpg
Feed Point
SWA10.jpg
Connector
SWA11.jpg
Protector
Station.jpg
Station
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